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Unit 3 Biology Notes
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Unit 3 Objectives: Cells II
1. Describe the important functions of organic molecules
 Carbohydrates

Lipids

Proteins

Nucleic acids
2. Explain how water is important to cells.
3. Describe the structure of the cell membrane and explain its importance in the transport of
materials into and out of the cell.
a. Phospolipid bilayer
b. Carrier molecules
c. Cell Membrane
4. Explain the purpose of cellular transport.
5. Define passive transport.
a. Diffusion
b. Osmosis
6. Describe how diffusion occurs and its importance in cell activity.
7. Describe how osmosis occurs and its importance in cell activity.
8. Given an example, be able to predict the direction of movement of materials through a
membrane.
9. Define and describe forms of active transport and their importance in cell activity.
a. Endocytosis
b. Exocytosis
10. Compare and contrast active and passive transport.
a. Examples
b. Energy required
c. Concentration gradient
11. Describe how cellular activity enables an organism to maintain homeostasis.
12. Explain the structure and function, or purpose, of an enzyme.
13. Describe the effects of pH and temperature on enzyme activity.
14. Review components of experimental design (see unit 1 objectives for criteria).
 Hypothesis
 Procedure
 Data Table
 Graph
 Conclusion
Key Terms:
Molecule
Inorganic
molecule
Organic molecule
Carbohydrate
Lipid
Protein
Nucleic Acid
Passive transport
Diffusion
Osmosis
Concentration
Concentration
gradient
Equilibrium
Active Transport
Endocytosis
Exocytosis
Cell Membrane
Semi-permeable
Phospholipid
Carrier protein
Homeostasis
Enzyme
Catalyst
Substrate
Active Site
Unit 3 Biology Notes
Organic Molecules
Objective 1: Describe the important functions of organic molecules
Organic Molecules: _________ atoms bonded to at least 1 _____________ atom.
Frequently bonded to oxygen or other carbon atoms.
Type of
Organic
Molecule
Carbohydrate
Lipid (Fat)
Nucleic Acid
Protein
Function of the Organic Molecule
Examples
Water
Objective 2: Explain how water is important to cells.
Water



Functions of Water (why water is important)
1.
2.
3.


4.

5.
 Turgor pressure (turgidity) =
 The pressure of the central vacuole in plant cells makes it possible for
plants to support heavy structures such as leaves and flowers.
6.

Cell Membrane
Objective 3: Describe the structure of the cell membrane and explain its importance in the
transport of materials into and out of the cell. (Phospolipid bilayer, Carrier molecules, Cell
Membrane)
The cell membrane is a ______________________________________________
that encloses the contents of the cell and
_________________________________________________________________.
Structure of the Cell Membrane:
 Primarily composed of a _________________________.
 ________________ are embedded in the bilayer.
Picture of the Cell Membrane:
The __________________________ of the cell membrane determines or
___________________________ what enters or leaves the cell.
Cell Transport
Objective 4: Explain the purpose of cellular transport.
Objective 5: Define passive transport. (Diffusion & Osmosis)
Objective 6: Describe how diffusion occurs and its importance in cell activity.
Purpose of Cell Transport:
 Moves _____________ material into and throughout a cell
 Moves unneeded ______________ out of a cell
 Moves _________ _______________ out of a cell
Passive Transport: the movement of material _________ or _________ a cell
without the use of the cell’s _____________. Molecules move from a _________
to ________ concentration to reach _____________________.
Diffusion: the movement of molecules from an area of ____________
concentration to an area of ___________ concentration to reach ______________.
Vocab Words:
Solute: the substance being _____________________ in a solution.
Solvent: the substance _____________________________ in a solution.
Concentration Gradient: the difference between the _________________ of a
particular molecule in _________ and its ________________ in ______________.
Equilibrium: when adjacent areas have an ________ concentration. There is
____________________ of molecules between the two areas. Each area is ______
with respect to the other.
How does diffusion work?
Diffusion occurs as a result of _________________________________________.
All molecules are in _____________________, and it is the __________________
_____________ - kinetic energy - that drives diffusion. Molecules that are
________________________ collide more frequently and will spread to the
_____________ concentration areas.
Why is diffusion important to our cells?
Diffusion is one way that materials _________cells and how some waste products
_____________the cell. It is important in transporting __________,
_____________ inorganic molecules such as __________, ___________, and
__________________ in and out of the cell to maintain _____________________.
Osmosis
Objective 7: Describe how osmosis occurs and its importance in cell activity.
Osmosis:
__________________________________________________________________
__________________________________________________________________.
How does osmosis work?
Through ________________, water molecules pass through the ______________
in cell membranes towards the _____________ water concentration area.
Why is osmosis important to our cells?
Osmosis is important in transporting water _________________________
the cell membrane to maintain _____________________.
Predicting Movement through a Membrane
Objective 8: Given an example, be able to predict the direction of movement of materials
through a membrane.
90% water
75% water
25% solutes
A
90% water
95% water
5% solutes
B
90% water
90% water
10% solutes
C
In A, water will ____________ the cell (_____% is greater than _____%)
In B, water will ____________ the cell (_____% is greater than _____%)
In C, the water concentrations are __________, so it is at _________________.
Active Transport
Objective 9: Define and describe forms of active transport and their importance in cell activity.
(Endocytosis & Exocytosis)
Active Transport: a type of cell transport in which ___________ is used to move
large or charged molecules across the cell membrane.
Reasons for Active Transport:
1. Materials need to be moved against the concentration gradient. (low
concentration to high concentration)
2. Materials are too large to pass through the membrane by diffusion, or they
are unable to pass through the membrane because of their charge.
Passage of Material using Carrier Proteins:
Carrier proteins and ___________ are used to pump ions and other molecules
across the cell membrane. These ions or molecules can be pumped
_____________ the concentration gradient.
Bulk Movement:
Large molecules are moved across the cell membrane by being packaged in large
sacs. 2 types: endocytosis & exocytosis.
Endocytosis: active transport processes that move large nutrients and materials
________ a cell
Exocytosis: active transport processes that move large wastes and cellular
products _________ a cell.
Comparing and Contrasting Passive and Active Transport
Objective 10: Compare and contrast active and passive transport. (Examples, Energy required,
& Concentration gradient)
How are passive transport and active transport alike?
1. Both are needed for the transport of certain molecules _____ and ________
the cell
2. Both are needed to help maintain ___________________.
How are passive transport and active transport different?
Passive Transport
Direction of Particle
Movement
Energy Usage
Characteristics of Molecules
Transported
Examples of Molecules
Transported
Active Transport
Homeostasis
Objective 11: Describe how cellular activity enables an organism to maintain homeostasis.
Homeostasis: ______________________________________________
**An organism is able to maintain homeostasis because of
_______________________.
**The external environment may change, but cells have mechanisms to keep the
internal conditions the same.
Examples of homeostasis at the cellular level:


Examples of homeostasis at the organism level:
 kidneys-osmoregulation (balancing the amount of water and dissolved
solutes)
 pancreas/liver- blood sugar
 body temperature regulation
 muscle contraction and relaxation - contributes to homeostasis by moving
materials from one place to another (blood, food, urine, etc.)
 blood chemistry – pH of the blood, contents of blood
 respiration rate – increases as cells require more O2
 heart rate – changes for various reasons, but primarily to pump more or less
blood around the body as needed
o more O2 required, heart rate increases
o conserve energy, heart rate decreases
o need to get chemical message somewhere fast, increase HR
 hormones – send messages to various cells
 buffers – regulate cell pH
 Etc.!
Enzymes
Objective 12: Explain the structure and function, or purpose, of an enzyme.
Objective 13: Describe the effects of pH and temperature on enzyme activity.
Catalyst:
substance that ______________, ____________, and ________________
chemical reactions without being ____________ itself
Enzyme:
Characteristics:
 How do they work?
o Enzymes speed up chemical reactions by ______________
the activation energy (energy needed to get a chemical
reaction started).
o Some enzymes cause compounds to _______________;
others cause compounds to be _________.
o Enzymes provide a way to _______________ life's
essential functions _____________ raising the temperature
of the organism's body and _____________ requiring more
energy.
 Lock & Key:
o
Substrate:
Active Site:
 Specificity:
 Work Quickly:
 Not changed:
 Enzyme Names:
Denaturation:
When an enzyme is exposed to ___________ heat or pH
values, it can ___________________, called becoming denatured. It will
no longer work the way it’s supposed to work.
Experimental Design
Objective 14: Review components of experimental design (see unit 1 objectives for criteria).
 Hypothesis
 Procedure
 Data Table
 Graph
 Conclusion